This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. This research is studying the effectiveness of a new treatment for severe breathing problems [respiratory failure], inhaled prostaglandins, in full-term and near-term newborns. This research will also help investigators to know if it is practical to study this therapy in a large number of infants. Immediately after birth, blood vessels which supply blood to the babys lungs go through changes that allow the full amount of blood to flow through the lungs. These changes happen because breathing stretches the lungs and increases the oxygen level, which causes certain hormone-like substances, called prostaglandins, to be made in the blood vessel walls. The blood vessels then relax and allow blood to flow freely. When a baby has severe breathing problems, the blood vessels in the lungs can squeeze tight and the lungs don't get enough blood. Investigators have been working for over 15 years to develop medical treatments to improve blood flow in the lungs of full-term and premature newborns with respiratory failure. Medications which relax blood vessels have been given intravenously. These help the lungs, but also relax blood vessels in other parts of the body where it is not helpful. Inhaled Nitric Oxide relaxes blood vessels in only the lungs because it is given directly into the lungs. This treatment has been very helpful, but can only be given for a limited time and requires special equipment. Intravenous medications that copy the body's own natural hormones, prostaglandins, have been used effectively and safely to treat certain heart conditions in newborns for over 20 years. Prostaglandins have now been tested in small studies where the PGE1 was given directly into the lungs, and the results are promising.